This invention relates to the manufacture of product gas in general.
More particularly, the invention relates to a method and apparatus for producing gas in a reactor by oxidation of finely divided fuel, with concomitant formation of liquid slag.
Still more specifically, this invention relates to a method and an apparatus for simultaneously cooling both the product gas and the liquid slag which are generated in a reactor under the aforementioned operating conditions.
It is known from the prior art to gasify in a reactor finely divided gas-suspended solid and liquid fuels to autothermally and at elevated pressure manufacture CO and H.sub.2 -containing product gases. The term "finely divided" is a term of art meaning that the fuels are present in form of small particles, in form of dust or, when liquid fuel is involved, in form of small droplets. If these fuels are of the high-ballast type, i.e. the type containing a high percentage of non-oxidizable residue (ash), then the level of the required reaction temperatures requires that these residues be converted into liquid slag so as to prevent their sinter deposition on portions of the reactor, because this could lead to blockage of the flow paths and/or to a reduction of the reactor volume. This liquid slag must be discharged from the reactor, either together with or independently of the product gas manufactured in the reactor.
To facilitate later handling, the liquid slag is cooled with water to cause it to solidify and become converted into slag granules. The problem with this is that it results in the formation of steam which tends to have a cooling effect on the oncoming liquid slag, increasing the viscosity of the same and leading to increased clogging of the slag outlets from the reactor.
A proposal has been made in German Published Application OS 2,723,601 to discharge the liquid slag from the reactor into a water-cooled tube whose lower end is immersed in a water bath, so that the slag becomes granulated when it drops into the water.
However, the subsequent uses of the product gas require that not only the slag but also the product gas itself be cooled, and this cannot be achieved with the aforementioned proposal.